A Level Biology Revision Notes

Comprehensive A Level Biology revision notes providing information and assistance for all UK examination boards (AQA, OCR, Edexcel) as well as international curriculum (CIE).

Join now →


Introduction Disaccharides are the carbohydrates that are made up of two monosaccharide subunits. They act as a source of monosaccharides. Sometimes, they also used as an alternative to monosaccharides as they share various common properties. In this section of the notes, we will discuss the structure, classification, and properties of disaccharides. We will also study …

Read article →Disaccharides


Polymers are the giant molecules formed by joining together of hundreds or thousands of smaller molecules. They belong to the category of macromolecules. The word polymer is derived from two Greek words; ‘poly’ meaning ‘many’, and ‘mer’ meaning ‘part’. Thus, a polymer is a large molecule made up of several identical repeating units called monomer. …

Read article →Polymers


Introduction Polysaccharides are the large biological molecules that belong to the category of carbohydrates. They are the biological polymers made up of hundreds or thousands of monosaccharide subunits attached via glycosidic bonds.  According to the definition, polysaccharides are the carbohydrates that contain more than ten monosaccharide subunits. Upon degradation, they yield individual monosaccharides.  Commonly occurring …

Read article →Polysaccharides


Introduction Monomers can be defined as small molecules that join together to form larger molecules. In order to completely understand the concept of monomers, let us first revise our definition of molecules. Molecules are defined as the stable pure particles formed by the chemical combination of two or more atoms. They can be either macro-molecules …

Read article →Monomers

Functions of Proteins

Functions of Proteins

Proteins are the most abundant organic molecules present on earth. They are present abundantly in every living cell. Proteins are the polymers made up of thousands of amino acids linked via peptide bonds. Long chains of amino acids known as polypeptides fold around themselves in several ways to form complex structures called proteins.  Functions performed …

Read article →Functions of Proteins

Structures of Blood Vessels

Summary The main artery in the heart is the aorta and arteries carry blood away from the heart Arterioles are smaller arteries that diverge into capillary beds Exchange of nutrients, waste and oxygen occur at the capillaries within tissues at cellular level Veins are blood vessels that return blood back to the heart; where venules …

Read article →Structures of Blood Vessels

Dipoles Of Water Molecules

Summary Water is the main constituent in all organisms A water molecule is said to be dipolar because it has a positive and a negative pole as a result of the uneven distribution of electrons within it The dipole nature within a water molecule creates attractive forces known as hydrogen bonding, allowing them to stick …

Read article →Dipoles Of Water Molecules


Summary To ensure that blood vessels don’t break when there is a cause of injury, a blood clot is crucial Blood clotting can also prevent you from bleeding to death which also protects you from bacterial and virial infection The process by which a blood clot is formed is called the coagulation cascade that involves …

Read article →Coagulation